Moire reduction with controlled perforation location

ABSTRACT

One or more perforation hole pattern methods are applied (402) to generate a spatial distribution of perforation holes forming a semi-random pattern for an image display screen. The image display screen is perforated (404) with the spatial distribution of perforation holes forming the semi-random pattern. Image rendering light is emitted (406) with a light projector toward the image display screen that is installed in an image rendering environment. At least a portion of the image rendering light emitted from the light projector is reflected (408) by the image display screen, toward a viewer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage entry of InternationalPatent Application No. PCT/US2021/045619, filed on Aug. 11, 2021, whichclaims priority of U.S. Provisional Patent Application No. 63/064,517,filed Aug. 12, 2020, and European Patent Application No. 20190641.9,filed Aug. 12, 2020, both of which are incorporated herein by referencein their entirety.

TECHNOLOGY

The present invention relates generally to image displays, and inparticular, to Moire reduction with controlled perforation location inimage displays or screens.

BACKGROUND

Screens in digital cinema installations have regular patternedperforations that allow sound waves from audio speakers behind thescreens to pass through toward viewers. In such a cinema installation,light that renders images may be emitted from a digital cinema projector(or any digital projector), projected onto such a screen, and reflectedfrom the screen toward the viewers. The light as emitted from theprojector onto the screen is modulated by a spatial distribution patternof amplitude variations of reflectivity of the screen. These amplitudevariations are at least in part impacted or influenced by presence ofthe perforations on the screen. When the perforations on the screen andvisual expressions of pixels from the projected images have spatialfrequencies forming rational relationships, visually perceptible beatsof lower spatial frequencies may occur and become quite noticeable. (Arational relationship is formed between a spatial frequency of a pixelpattern and a spatial frequency of a perforation pattern if a ratio ofthe two spatial frequencies can be represented as a ratio of two integernumbers.) This type of visual artifact, known as Moire pattern, is notdepicted or intended to be depicted by content creators in the imagesbut rather is induced by certain relationships and interactions betweenspatial frequencies or variations of the perforation pattern and spatialfrequencies or variations of image features or textures in the images.

The approaches described in this section are approaches that could bepursued, but are not necessarily approaches that have been previouslyconceived or pursued. Therefore, unless otherwise indicated, it shouldnot be assumed that any of the approaches described in this sectionqualify as prior art merely by virtue of their inclusion in thissection. Similarly, issues identified with respect to one or moreapproaches should not assume to have been recognized in any prior art onthe basis of this section, unless otherwise indicated.

BRIEF DESCRIPTION OF DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1A illustrates an example modified fixed perforation pattern; FIG.1B illustrates an example square pixel pattern superimposed with amodified fixed perforation pattern; FIG. 1C illustrates an example Moirepattern that may be generated with a pixel pattern such as illustratedin FIG. 1B;

FIG. 2A illustrates an example semi-random perforation pattern; FIG. 2Billustrates an example square pixel pattern superimposed with asemi-random perforation pattern; FIG. 2C illustrates an example Moirepattern that may be generated with a pixel pattern such as illustratedin FIG. 2B;

FIG. 3A illustrates an example cinema; FIG. 3B illustrates an examplescreen;

FIG. 4 illustrates example process flows; and

FIG. 5 illustrates an example hardware platform on which a computer or acomputing device as described herein may be implemented.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments, which relate to Moire reduction with controlledperforation location, are described herein. In the followingdescription, for the purposes of explanation, numerous specific detailsare set forth in order to provide a thorough understanding of thepresent invention. It will be apparent, however, that the presentinvention may be practiced without these specific details. In otherinstances, well-known structures and devices are not described inexhaustive detail, in order to avoid unnecessarily occluding, obscuring,or obfuscating the present invention.

Example embodiments are described herein according to the followingoutline:

-   -   1. GENERAL OVERVIEW    -   2. REGULAR PERFORATION PATTERNS    -   3. SEMI-RANDOM PERFORATION PATTERNS    -   4. SYSTEM CONFIGURATION    -   5. EXAMPLE PROCESS FLOWS    -   6. IMPLEMENTATION MECHANISMS—HARDWARE OVERVIEW    -   7 EQUIVALENTS, EXTENSIONS, ALTERNATIVES AND MISCELLANEOUS

1. General Overview

This overview presents a basic description of some aspects of an exampleembodiment of the present invention. It should be noted that thisoverview is not an extensive or exhaustive summary of aspects of theexample embodiment. Moreover, it should be noted that this overview isnot intended to be understood as identifying any particularlysignificant aspects or elements of the example embodiment, nor asdelineating any scope of the example embodiment in particular, nor theinvention in general. This overview merely presents some concepts thatrelate to the example embodiment in a condensed and simplified format,and should be understood as merely a conceptual prelude to a moredetailed description of example embodiments that follows below. Notethat, although separate embodiments are discussed herein, anycombination of embodiments and/or partial embodiments discussed hereinmay be combined to form further embodiments.

Under techniques as described herein, perforation locations on a screenor image display may be generated in a semi-random pattern such thatMoire patterns are reduced or eliminated. Perforation holes punched ormade on the screen in these locations allow sound (waves) generated by(audio) speakers behind the screen to propagate relative freely toviewers/audience. The screen may be installed in a cinema, movietheatre, entertainment venue, amusement park, and so on, where Moire isa significant problem.

In some operational scenarios, halftone techniques may be used toproduce or generate perforation locations in a semi-random pattern thatis spatially random but with no or little low frequency pattern thatcould be visually observable on a screen as non-uniformity on thescreen. These techniques can provide uniformity in perforation holedistribution, reduce or avoid Moire patterns to be generated in imagerendering operations, while maintaining needed perforation density andarea for the sound to pass from behind the screen.

In some operational scenarios, noise generation/injection techniques maybe used to modify a regular perforation pattern such as the commerciallyavailable Digital Perforation or standard perforation pattern such thatthe resultant perforation locations do not form a regular grid prone toinducing Moire patterns. Additionally, optionally or alternatively,filtering may be applied to generate high pass filtered spatial randomor semi-random noise (e.g., with a uniform amplitude distribution, etc.)that can be added to x and y locations of grid points or vertexes of theregular perforation grid.

A selected amount of high pass filtered noise may be implemented toreduce or prevent non-uniformity of the resultant semi-random patternvisible on the screen for viewers at or beyond a designated distance,taking into account that visual features in a rendered image on thescreen are further low pass filtered by the Human Visual System at orbeyond the designated distance. Additionally, optionally oralternatively, the selected amount of noise can be set to besignificantly less than the perforation pitch of the regular perforationgrid, for example to avoid placing perforation locations at an edge of aweb used to form the screen.

Perforation locations as described herein may be derived based upon an(existing logical but not physically visible) reference perforation gridon a screen made of one or more screen material webs (e.g., cut fromrolls of screen materials, etc.). Cuts and joins of screen material websto form the screen can be carried out in reference to the original gridpoint locations in the reference perforation grid without introducing DCshifts impacting the uniformity of the reference perforation gridlogically imposed onto the screen. Thus, the screen material webs can beseamed, stitched and/or welded in reference to the reference perforationgrid without generating visible artifacts caused by DC shifts in theresultant screen.

Furthermore, semi-random perforation location generation techniques suchas noise generation/injection techniques, halftone techniques, etc., maybe modified and/or combined to reduce the amplitude of noises or spatialdisplacements from regular grid points or vertexes, as one approachesedges of webs. Thus, the locations of the perforations can trend orsimply cutover to the original regular perforation pattern toward theedges of the webs to avoid creating visible artifacts around the edgesof webs such as half perforations, visible misalignments, and so on.

Example embodiments described herein relate to image display systems. Animage display system comprising: an image display screen that comprisesa spatial distribution of perforation holes forming a semi-randompattern; a light projector that emits image rendering light toward theimage display screen. The image display screen reflects at least aportion of the image rendering light emitted from the light projectortoward a viewer.

Example embodiments described herein relate to image display systems.One or more perforation hole pattern methods are applied to generate aspatial distribution of perforation holes forming a semi-random patternfor an image display screen. The image display screen is perforated withthe spatial distribution of perforation holes forming the semi-randompattern. Image rendering light is emitted, by a light projector, towardthe image display screen that is installed in an image renderingenvironment. At least a portion of the image rendering light emittedfrom the light projector is reflected, by the image display screen,toward a viewer.

Example embodiments described herein relate to image display screenconfigured to reflect at least a portion of image rendering lightemitted from a light projector toward a viewer, the image display screencomprising a spatial distribution of perforation holes forming asemi-random pattern to reduce Moire patterns in image renderingoperations.

In an embodiment, the image display screen comprises a plurality of websthat are joined along one or more seam edges. In an embodiment, thespatial distribution of perforation holes on the image display screentrends to or cuts over from the semi-random perforation pattern to aregular perforation pattern toward the one or more seam edges.

Example embodiments described herein relate to a method of manufacturingan image display screen, comprising: applying one or more perforationhole pattern methods to generate a spatial distribution of perforationholes forming a semi-random pattern for the image display screen toreduce Moire patterns in image rendering operations; perforating theimage display screen with the spatial distribution of perforation holesforming the semi-random pattern; and providing a plurality of webs thatare joined along one or more seam edges of the image display screen. Thespatial distribution of perforation holes on the image display screentrends or cuts over from the semi-random pattern to a regularperforation pattern toward the one or more seam edges.

Various modifications to the preferred embodiments and the genericprinciples and features described herein will be readily apparent tothose skilled in the art. Thus, the disclosure is not intended to belimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features described herein.

2. Regular Perforation Patterns

Strength and visibility of Moire patterns generated from interactionbetween perforations on a screen and visual expressions of pixels in animage projected from a projector onto and reflected from the screen isdependent upon relative spacings of a pixel pattern of the pixels fromthe projector and a perforation pattern of the perforations, size of theperforations, (e.g., luminance, chrominance, etc.) amplitude of thepixel pattern from the projector. The worst Moire pattern can occur as aresult of the perforation pattern with a spatial pitch forming arational relationship to a spatial pitch of the pixel pattern. Forexample, a visually noticeable beat or Moire pattern is prone to occurwhen the perforation pattern is of a spatial pitch similar to or amultiple of a spatial pitch of the pixel pattern.

A method for reducing or preventing Moire patterns may be referred to asa de-Moire method. One example de-Moire method is to defocus projectionlens in a projector. This method could work to reduce the Moire patternbut at the risk of unnecessarily reducing the overall resolution of theimage. When the lens is defocused, the lens' modulation transferfunction (MTF) can be significantly changed in a device or designdependent/sensitive manner. While one would expect de focus to onlyaffect relatively high spatial frequencies (e.g., in or toward an upperpart of a full spatial frequencies perceivable by human vision, etc.),it can also affect relatively low spatial frequencies (e.g., in ortoward a lower part of the full spatial frequencies perceivable by humanvision, etc.), depending upon the projection lens design. For example,relatively low spatial frequencies in visual expressions of pixels inthe projected image may sometimes be affected by such a de-Moire method.

In practice, it may be difficult to achieve a proper amount ofdefocusing in a projection lens while also attempting to strike abalance between de-Moire and defocusing. A cinema or theater may beoperated by multiple maintenance technicians. Refocusing or defocusingprojection lens may be one of the first things performed by amaintenance technician coming in to perform operational duty of thecinema or theatre. The technician may not be familiar with the Moirepattern problem, previous adjustments used to reduce the problem, oreffects of the previous adjustments on the Moire pattern problem andprojected image resolution. Thus, it is unlikely for the technician todetermine whether a proper amount of refocusing or defocusing hasalready performed or is to be performed. It is also unlikely for thetechnician to determine whether performed or to-be-performed refocusingor defocusing serves to reduce or exacerbate the Moire pattern problem.

Another example de-Moire method is to use a modified fixed perforationpattern, such as the Digital Perforation pattern (e.g., Harkness, etc.),to reduce the Moire pattern.

FIG. 1A illustrates an example modified fixed perforation patternrepresented in a two-dimensional space with vertical and horizontalspatial dimensions. The modified perforation pattern comprises atwo-dimensional array of perforations each of which is represented by asolid black circle in FIG. 1A. Different from a standard square orrectangular perforation pattern, the modified perforation pattern hasalternate (perforation) rows with a ½ perforation spatial offsetcompared with neighboring (perforation) rows. Likewise, the modifiedperforation pattern has alternative (perforation) columns with a ½perforation spatial offset compared with neighboring (perforation)columns. The ½ perforation spatial offset used for alternating(perforation) rows may, but is not required to, be different from the ½perforation spatial offset used for alternating (perforation) columns.

FIG. 1B illustrates an example square pixel pattern superimposed with amodified fixed perforation pattern (e.g., in FIG. 1A, etc.). The squarepixel pattern comprises a two-dimensional array of pixels each of whichis represented by a white square in the square pixel pattern FIG. 1B.Perforations (solid black circles in FIG. 1B—which may be the same asthose in FIG. 1A) along a (perforation) column in the modifiedperforation pattern have varying spatial offset in relation topixels—e.g., white squares in which the perforations are embedded or atleast partly overlapped—along a corresponding pixel column in the pixelpattern. Likewise, perforations (solid black circles) along a(perforation) row in the modified perforation pattern has varyingspatial offset in relation to pixels—e.g., white squares in which theperforations are embedded or at least partly overlapped—along acorresponding pixel row in the pixel pattern.

A modified fixed perforation pattern such as illustrated in FIG. 1A andFIG. 1B can (still) be prone to generating Moire patterns. FIG. 1Cillustrates an example Moire pattern that may be generated when visualexpressions of pixels in a pixel pattern such as illustrated in FIG. 1Bcomprises spatial frequencies that are of a rational relationship withspatial frequencies of the modified fixed perforation pattern. The Moirepattern as illustrated in FIG. 1C may be especially pronounced or theworst when the spatial frequencies of the pixel pattern or visualexpressions of pixels and the spatial frequencies of the perforationpattern of FIG. 1A or FIG. 1B are similar or multiples of each other.

As used herein, a visual expression of a pixel may refer to colors,luminance, and/or chrominance of the pixel as rendered on the screen.The visual expression of the pixel may be set based on a pixel value ofthe pixel received in image data in movie/image/video displayoperations.

While improving over a standard square or rectangular perforationpattern, the modified fixed perforation pattern is unlikely tosufficiently lessen or eliminate the Moire pattern problem, for examplein cinemas, movie theatres or the like.

3. Semi-Random Perforation Patterns

Under techniques as described herein, perforation locations on a screenor image display (e.g., image display, 60-feet cinema screen, etc.) canbe generated or implemented in a semi random fashion such that a Moirepattern is not produced or is minimized on the screen in image renderingoperations.

FIG. 2A illustrates an example semi-random perforation pattern forperforation holes made on a screen or image display represented in atwo-dimensional space with vertical and horizontal spatial dimensions.The semi-random perforation pattern comprises a two-dimensional(semi-random) spatial distribution of perforations each of which islogically represented by a solid black circle of FIG. 2A. A perforationhole as described herein as actually drilled or implemented on a screenmay be of any in a variety of closed shapes including but not limited tocircular shapes, oblong shapes, polygon shapes, irregular shapes, etc.In some operational scenarios, a perforation hole may be circular inshape and of a specific dimension, size or diameter that is selected tobe below the spatial resolution (or angular resolution) of a (human)viewer beyond a specific viewing distance in a venue. Image displayoperations in the venue are performed with one or more projectors toproject 2D or 3D images onto the screen or image display, which reflectat least a portion of the incident light toward viewers for the purposeof rendering images visible to the viewers.

Different from perforation patterns (e.g., standard square/rectangleperforation pattern, modified perforation pattern, etc.) under otherapproaches, the semi-random perforation pattern of FIG. 2A comprisesperforation holes with no visually discernible regular pattern (e.g.,crosshatch pattern, etc.) and nonetheless appears uniform to a (human)viewer of a sufficiently far distance.

As used herein, “uniform” may refer to a perforation hole density on thescreen being uniform (e.g., within a tolerance of 0.1%, 1%, 2% oranother percentile, etc.). Additionally, optionally or alternatively,“uniform” may refer to the total number of perforation holes per unitarea of the screen being uniform. Here, a unit area used to measureuniformity may be: comparable to an area distinguishable by human eyes(e.g., as represented with the Human Visual System or HVS, etc.);smaller than an area distinguishable by human eyes; etc.

A regular pattern as described herein may refer to a pattern formedthrough repetition of constant spatial offsets. Example regular patternsmay include, but are not necessarily limited to only, any of: crosshatchpatterns, square or rectangular patterns, matrix patterns, diagonalpatterns, concentric patterns, combinations of regular patterns with orwithout offsets, and so forth.

A visually discernible regular pattern may refer to a regular pattern(or a regular pattern portion) that is of a (pattern) size, dimensionand/or regularity of repetitions visibly discernible within the spatialresolution capability (e.g., in retina vision, in foveal vision, etc.)of the Human Visual System.

FIG. 2B illustrates an example square pixel pattern superimposed with asemi-random perforation pattern (e.g., in FIG. 2A, etc.). As previouslynoted, the square pixel pattern comprises a two-dimensional array ofpixels each of which is represented by a white square in the squarepixel pattern. Perforations (solid black circles) in the semi-randomperforation pattern has varying individual spatial displacements inrelation to pixels—e.g., white squares in which the perforations areembedded or at least partly overlapped—in the pixel pattern.

A semi-random perforation pattern such as illustrated in FIG. 2A andFIG. 2B may be used to eliminate or greatly reduce visual artifactsrelating to Moire patterns. FIG. 2C illustrates an example (worst case)Moire pattern that may be generated when visual expressions of pixels ina pixel pattern such as illustrated in FIG. 2B. Rational relationshipsthat induce Moire patterns are difficult to form to a sufficientlysignificant extent between spatial frequencies in visual expressions ofa pixel pattern and spatial frequencies of the semi-random perforationpattern to generate visual artifacts relating to the Moire pattern giventhat perforation holes in the semi-random perforation pattern aredistributed irregularly or visually random. As a result, the Moirepattern as illustrated in FIG. 2C may be absent or much less severe thanthat of FIG. 1C and thus may be invisible to or much less visuallynoticed by viewers in actual image rendering operations.

One or more perforation location generation methods may be usedindividually or in combination by a system as described herein togenerate perforation locations of a semi-random pattern on a screen orimage display. In some operational scenarios, a perforation locationgeneration method may be a halftone method implementing any combinationof one or more halftoning techniques including but not limited to:dithering techniques, void-and-cluster techniques, tessellationtechniques, stochastic screening, direct binary search (DBS) techniques,error diffusion techniques, frequency modulated (FM) techniques, etc.

4. System Configuration

FIG. 3A illustrates an example cinema 300. Two-dimensional and/orthree-dimensional image/video content may be rendered with one or moreprojectors (e.g., 316, digital laser projector or DLP, etc.) deployed inthe cinema (300). A projector (e.g., 316, etc.) as described herein maycomprise light engine, prism, optics, digital micromirror device or DMD,etc., to generate and project light onto a screen (e.g., an imagedisplay, etc.) 314. The projected light from the projector (316) isreflected off from the screen (314) toward one or more viewers in aviewer area (e.g., an audience area, a seated area, a designated area,etc.) 312. One or more speakers 318 may be placed or located behind thescreen (314). These speakers (318) emit sounds that depict sounds fromaudio sources (e.g., characters, instruments, objects, etc.) locatedwithin, within and/or outside a visual scene depicted in the imagesrendered by the projected light from the projector (316) onto the screen(314). The screen (314) may be made of a single web or multiple webs invarious embodiments.

FIG. 3B illustrates an example screen (e.g., 314 of FIG. 3A, imagedisplay, etc.) that is seamed, stitched and/or welded together with aplurality of webs (e.g., 302-1 through 302-4, etc.). Neighboring webs(e.g., 302-1 and 302-2, 302-2 and 302-3, etc.) in the plurality of websmay be physically joined along seams (e.g., 306, etc.). Each web—e.g.,as derived or cut from a roll of a specific screen material, a width ofone yard from a roll of a specific screen material, etc.—in some or allof the plurality of webs may be logically partitioned to form aplurality of sections (e.g., 310, etc.) in an overall reference pattern304. For the purpose of illustration only, the reference pattern (304)may be a rectangular grid pattern. The reference pattern (304) may notbe physical but rather logical and thus may not possess visual featuresvisible to a viewer. The reference pattern (304) or the sections (e.g.,310, etc.) therein, may be used as a starting point or an initialcondition to generate perforation locations in a semi-random pattern.

As illustrated in FIG. 3B, each section in some or all of the pluralityof sections (e.g., 310, etc.) may be further logically (e.g., invisibly,etc.) partitioned into candidate positions (e.g., 308, etc.) some ofwhich may be selected or identified as locations for placing orimplementing perforation holes. Perforation locations in the semi-randompattern may be selected, using a perforation generation method asdescribed herein, from a set of candidate positions (e.g., 308, etc.) inthe plurality of sections (e.g., 310, etc.) in the reference pattern(304).

A location of a section (e.g., 310, etc.) in the reference pattern (304)may be specified or defined (e.g., with array indexes, with coordinatevalues, with index values, with row and column values, etc.) in relationto the reference pattern (304), such as an upper left grid point orvertex of the reference pattern (304). Likewise, a perforation locationmay be specified or defined (e.g., with array indexes, with coordinatevalues, with index values, with row and column values, etc.) in relationto grid points or vertices of the regular grid pattern (304), such as anupper left grid point or vertex of a section in which the perforationlocation resides.

For example, a plurality of candidate locations (e.g., 308, etc.) mayreside in a section of the reference pattern (304). The section may beone of the plurality of sections (e.g., 310, etc.) that form atwo-dimensional (2D) section array as illustrated in FIG. 3B. In someoperational scenarios, the location of the section may be specified ordefined—in relation to the upper left grid point or vertex of thereference pattern (304)—with section array indexes (or a 2D index, etc.)one of which is along the horizontal direction of the 2D section arrayand the other which is along the vertical direction of the 2D sectionarray.

A candidate location (e.g., 308, etc.) may be one of a plurality ofcandidate locations that reside in a section as illustrated in FIG. 3Band form a two-dimensional (2D) candidate location array in the section.The candidate location (e.g., 308, etc.) residing in the section may beidentified by the location of the section as specified by the sectionarray indexes of the section plus the (relative) location of thecandidate location (e.g., 308, etc.)—in relation to the upper left gridpoint or vertex of the section—with candidate location array indexes (ora 2D index, etc.) one of which is along the horizontal direction of the2D candidate location array in the section and the other which is alongthe vertical direction of the D candidate location array in the section.

Perforation locations can be generated using a perforation generationmethod as described herein. The perforation locations can be selected,from some or all candidate locations in some or all sections of thereference pattern (304), as a (e.g., proper, etc.) subset of candidatelocations in the candidate locations of the reference pattern (304) suchthat the perforation locations are placed with varying individualspatial displacements in relation to sections (in the reference pattern(304)) in which the perforation locations reside to form a semi-randompattern different from the reference pattern (304).

In some operational scenarios, a perforation generation method asdescribed herein may implement or utilize (e.g., iterative, recursive,etc.) halftone techniques such as Ulichney's void-and-cluster initialpattern (VACip) techniques to generate a semi-random pattern. Thehalftone techniques may be applied to the entire screen as a whole or apart (e.g., web, a group of contiguous sections on a single fabric webor multiple webs, etc.) thereof individually. These techniques can beused to produce, from candidate locations of the screen or imagedisplay, patterns that are spatially random (e.g., as compared with thereference pattern (304), as compared with a regular pattern, etc.).Additionally, optionally or alternatively, these techniques can beimplemented to avoid or significantly reduce low frequency patterns thatmight be observable on the screen as non-uniformity on the screen.

A semi-random perforation pattern generated with halftone techniquesprovides or maintains uniformity in terms of perforation density (on ascreen or image display), the total number of perforations over a unitarea (on the screen or image display) comparable or below what the HVScan spatially resolve, and so on. Image rendering operations on thescreen or image display with the semi-random perforation pattern sogenerated produce no or little Moire patterns. In addition, uniformperforation density and corresponding aggregated perforated area on arelatively fine scale—e.g., a unit area comparable to or below what aviewer's vision can spatially resolve, etc.—allow sound from speakersbehind the screen to pass with no or little impedance.

Perforation tools used to drill, punch, or otherwise make perforationholes on a screen or a web thereof may be driven with perforationlocation data specifying perforation locations generated by halftonetechniques as described herein.

In some operational scenarios, a perforation generation method asdescribed herein may implement noise generation techniques to generate asemi-random pattern. Noises can be generated with the noise generationtechniques and used to modify a reference perforation pattern—which mayor may not be the same as the reference pattern of FIG. 3B, etc.—thatcontains a designated (e.g., uniform, etc.) density of perforationholes—into the semi-random pattern. The reference perforation patternmay be the same as the commercially available Digital PerforationPattern or another standard perforation pattern such as a regularperforation grid (or a perforation grid of regular pattern), which maybe prone to generating Moire patterns in image rendering operations.

More specifically, the noise can be used to generate varying spatialdisplacements to different locations (e.g., represented with spatialdimensions x and y, etc.) of grid points (or vertices) in the regularperforation grid. The noises can be high frequency noises with asufficient amount to reduce or avoid Moire patterns but not large enoughto increase non-uniformity in perforation hole distribution on thescreen.

In some embodiments, the noises may be generated with high passfiltering (e.g., with a two-dimensional filter, with a kernel separablefilter, etc.) with a uniform amplitude distribution (e.g., in passedfrequencies, with a maximum allowable distance from a reference regulargrid point or vertex, with a maximum allowable distance from a referenceregular grid line, etc.) to reduce non-uniformity of the semi-randompattern on the screen when viewed at a distance (low pass filtered bythe human eye). Amplitudes of the noises along different spatialdirections may be different or same. For example, an amplitude of thenoises along a spatial axis x may be set differently from or the same asan amplitude of the noises. Additionally, optionally or alternatively,angles of spatial displacements as described herein may be generated orderived from the noises.

Filtering operational parameters (e.g., cutoff frequency, amplitude,filter coefficients, number of filter taps, etc.) for the high passfiltering may be set, selected and/or determined through computer-aidedmodeling (e.g., MATLAB simulations, etc.) or empirical studies.

For example, the filtering operational parameters may be varied inranges, values, etc., to determine whether semi-random patternsgenerated from these varied filtering operational parameters interactwith visual content rendered on the screen to generate visuallysignificant Moire patterns. In the meantime, other non-filteringoperational parameters such as types and/or sizes of screens, viewingdistances, numbers of webs, types of webs, image resolutions (e.g., 4K,8K, etc.), makers, types and/or models of projectors, densities, sizesand/or shapes of perforation holes, numbers and types of speakers,focusing and/or defocusing of projection lenses, and so on, may be fixedor varied, while values for the filtering operational parameters arebeing varied and tried, to determine or select optimal values for thefiltering operational parameters among the varied and tried values. Theoptimal values for the filtering operational parameters may generatesufficient noises to avoid or reduce Moire patterns in test images orreal images used in optimization operations and to avoid or reduce anynon-uniformity that may be introduced by the injection of noises intospatial locations of the perforation holes. Thus, spatial variationsand/or noises in spatial locations of perforation holes may be generatedand distributed on a screen or image display in a semi-random manner(e.g., with a halftoning or noise injection algorithm with optimizedoperational parameter values, etc.) as opposed to in a true-randommanner.

A semi-random perforation pattern generated with noisegeneration/injection techniques provides or maintains uniformity interms of perforation density (on a screen or image display), the totalnumber of perforations over a unit area (on the screen or image display)comparable or below what the HVS can spatially resolve, and so on. Imagerendering operations on the screen or image display with the semi-randomperforation pattern so generated produce no or little Moire patterns. Inaddition, uniform perforation density and corresponding aggregatedperforated area on a relatively fine scale—e.g., a unit area comparableto or below what a viewer's vision can spatially resolve, etc.—allowsound from speakers behind the screen to pass with no or littleimpedance.

Perforation tools used to drill, punch, or otherwise make perforationholes on a screen or a web thereof may be driven with perforationlocation data specifying perforation locations generated by noisegeneration/injection techniques as described herein.

In some operational scenarios, an amount of noise representing spatialdisplacements relative to regular grid points (or vertices) in a regularperforation pattern can be controlled to be significantly less than(e.g., ⅛, ¼, ½, etc.) the perforation pitch in the regular perforationpattern. This may be used to reduce or avoid presence of perforation(hole) locations at an edge of a web.

In operational scenarios in which perforation locations are derivedbased upon a reference grid or pattern such as reference perforationgrid, cuts and joins of webs used to combined, seamed, stitched and/orwelded into an overall screen (or image display) can be made based upongrid locations represented in the reference grid or pattern withoutintroducing DC shifts (e.g., pitches along a seaming edge of twoadjoining webs are shifted by a constant offset, etc.) that affectsuniformity of an overall regular pattern of the screen or uniformity ofa semi-random pattern of the screen generated from the regular patternof the screen through noises or varying spatial displacements. As aresult, screen materials such as webs can be seamed, stitched and/orwelded without producing visible artifacts.

In some operational scenarios, noise generation techniques used togenerate a semi-random perforation hole pattern may be modified toreduce the amplitude of noises as one approaches an edge of a web suchthat locations of perforations trend to a regular perforationpattern—from which the semi-random perforation is generated by varyingspatial displacements corresponding to the noises—toward the edge of theweb. An extreme example may be to simply cutover to the (original)regular perforation grid toward the edge of the web. In other words, thespatial distribution of perforation holes on the image display screentransits (e.g. continuously) from the semi-random perforation pattern toa regular perforation pattern toward the edge of the web, e.g. at theseam edges. Any of these modifications may be used to prevent creatingvisible artifacts at the edge of the web when joining with an adjacentweb, as both sides of the edge in the web and its adjacent webconverges, trends and/or cutover to the same (original pre-modified)regular perforation grid.

Likewise, in some operational scenarios, halftone techniques used togenerate a semi-random perforation hole pattern may be modified toreduce the strength of halftone (or dithering) operations as oneapproaches an edge of a web such that locations of perforations trend toa regular perforation pattern—from which the semi-random perforation isgenerated by halftoning or dithering—toward the edge of the web. Inother words, the spatial distribution of perforation holes on the imagedisplay screen transits (e.g. continuously) from the semi-randomperforation pattern to a regular perforation pattern toward the edge ofthe web, e.g. at the seam edges. These modifications may be used toprevent creating visible artifacts at the edge of the web.

In some operational scenarios, halftone techniques may possibly resultin incomplete perforations (e.g., half perforations, etc.) along edgesof a web among multiple webs seamed, stitched and/or welded into thescreen. A halftoning algorithm may use constructs such ascircles/spheres to cover neighboring areas when filling voids withperforation holes or avoiding congestion of too many perforations in anexisting cluster of perforation holes. For example, the halftoningalgorithm may operate to favor placing perforation holes in voids anddisfavor placing perforation holes in clusters extending over multipleadjacent areas or regions of a screen. As a result, some perforationholes may be placed by the halftoning algorithm along an edge of twoadjoining webs. In practice, half perforation holes or incompleteperforation holes on the two adjoining webs may not be matched exactly,resulting in the half or incomplete perforation holes (e.g., possiblyvisibly, etc.) appearing along the edge of the webs. In some operationalscenarios, injection or generation of noise such as high frequency noiseinto locations of perforation holes may be constrained so that theperforation holes in a semi-random pattern of a screen as describedherein are located within a single web without leaving half orincomplete perforation holes along edges of webs on the screen.

For the purpose of illustration only, it has been described that ascreen may be of a rectangular shape. It should be noted, however, thatin various embodiments, semi-random perforation hole patterns may beimplemented in screens of rectangular or non-rectangular shapes, regularor non-regular shapes, curved or planar shapes, and so forth.

For example, under other approaches, a regular perforation pattern isimplemented for or in a curved or domed image display, Moire patternproblems could become pronounced and easily noticeable in certain areasof the curved or domed image display, because of the relatively highlikelihood of existence of rational relationships (e.g., similarity,multiplicity, etc.) between spatial frequency responses of the regularperforation pattern and spatial frequencies in visual expressions of thepixels.

In contrast, under techniques as described herein, a semi-randomperforation hole pattern ay be implemented with a curved or domed imagedisplay in which pixels may not be formed by square-shape screen door(or black strips surrounding pixels in white squares) as illustrated inFIG. 2B but rather may be formed by other shapes of constant or varyingsizes depending locations of the pixels on the curved or domed imagedisplay. Such a semi-random pattern can be used with the curved or domedimage display to lessen or prevent Moire pattern problems, to provideuniformity of perforation holes for sound propagation, to reduce orprevent visual artifacts along edges/seams or elsewhere on the display.

A wide variety of materials may be used (e.g., as webs, etc.) by ascreen or image display as described herein. Example materials mayinclude, but are not necessarily limited to only, any of: syntheticmaterials, plastic or vinyl materials, washable materials, seamedmaterials, stitched materials, welded materials, materials joined withflat or invisible seams, coated grain screen materials, polarized silverscreen materials, laser projection screen materials, woven materials,non-woven materials, random woven materials or materials with randomwoven patterns, natural or non-natural materials, etc.

Pixel sizes (or sizes of pixels such as white squares of FIG. 2B) of ascreen (e.g., a 60-ft screen, a 50-ft screen, a 10-ft screen, etc.) mayentirely or partly depend on image resolution of images rendered on thescreen and the size of the screen. Perforation sizes and densities mayentirely or partly depend on an audio configuration (e.g., speakerconfiguration, etc.) deployed with the screen (e.g., in FIG. 3A, etc.).Densities and sizes of perforation holes on the screen may bespecifically selected to be sufficiently large to allow sound topropagate from speakers behind the screen to viewers/listeners andsufficiently small to make the perforation holes not visuallysignificant or perceivable to the viewers/listeners. In some operationalscenarios, pixels on a screen as described herein may have a finerspatial resolution than perforation holes on the screen; for example,pixel sizes may be greater than average spacing or distance between oramong the perforation holes. In some operational scenarios, pixels on ascreen as described herein may have a coarser spatial resolution thanperforation holes on the screen; for example, pixel sizes may be smallerthan average spacing or distance between or among the perforation holes.In some operational scenarios, pixels on a screen as described hereinmay have a comparable spatial resolution to that of perforation holes onthe screen.

For the purpose of illustration only, it has been described that asemi-random perforation hole pattern may be generated by either ahalftone method or a noise generation/injection method. It should benoted that, in various embodiments, other methods such as a combinationof halftone and noise generation methods may be used to generate asemi-random perforation hole pattern. For example, a noisegeneration/injection method may be applied from a pattern generated froma halftone method instead of a regular grid pattern. Additionally,optionally or alternatively, a halftone method may be applied from apattern generated from a noise generation/injection method.

5. Example Process Flows

FIG. 4 illustrates an example process flow according to an exampleembodiment of the present invention. In some example embodiments, asystem—which comprises one or more of: computing devices or components,perforation tools, drilling tools, seaming tools, welding tools,stitching tools, screen material assembly tools, image processingsystems, image projectors, audio systems, etc.—may perform this processflow. In block 402, the system applies one or more perforation holepattern methods to generate a spatial distribution of perforation holesforming a semi-random pattern for an image display screen to reduceMoire patterns. The semi-random pattern represents a spatially randomperforation pattern free of relatively low frequency patterns prone togenerate the Moire patterns in the image rendering operations. As usedherein, “low frequency”, “relatively low frequency,” “low spatialfrequency”, “relatively low spatial frequency,” and so forth, refer tospatial frequencies in or toward the lower part of a full spatialfrequency spectrum visually perceptible to HVS. Alternatively orequivalently, “low frequency”, “relatively low frequency,” “low spatialfrequency”, “relatively low spatial frequency,” and so forth, may referto spatial frequencies (e.g., spatial frequencies in a semi-randomperforation patter, etc.) that form rational relationships such ascomparable to or multiple of spatial frequencies in image features ofrendered images thereby generating Moire patterns in image renderingoperations. Conversely, “high frequency”, “relatively high frequency,”“high spatial frequency”, “relatively high spatial frequency,” and soforth, refer to spatial frequencies in or toward the upper part of afull spatial frequency spectrum visually perceptible to HVS.Alternatively or equivalently, “high frequency”, “relatively highfrequency,” “high spatial frequency”, “relatively high spatialfrequency,” and so forth, may refer to spatial frequencies (e.g.,spatial frequencies in a semi-random perforation patter, etc.) that donot form rational relationships such as comparable to or multiple ofspatial frequencies in image features of rendered images therebyavoiding or reducing Moire patterns in image rendering operations.

In block 404, the system perforates the image display screen with thespatial distribution of perforation holes forming the semi-randompattern. In block 406, the system emits, by a light projector, imagerendering light toward the image display screen that is installed in animage rendering environment.

In block 408, the system reflects, by the image display screen, at leasta portion of the image rendering light emitted from the light projectortoward a viewer.

Blocks 402 and 406 without blocks 406 and 408 represent the steps of amethod of manufacturing an image display screen. Such method ofmanufacturing the image display screen may further comprise (not shownin FIG. 4 ) the additional step of providing a plurality of webs thatare joined along one or more seam edges of the image display screen. Thespatial distribution of perforation holes on the image display screentrends to or cuts over from a semi-random perforation pattern to aregular perforation pattern toward the one or more seam edges.

In an embodiment, an image display system comprises: an image displayscreen that comprises a spatial distribution of perforation holesforming a semi-random pattern; a light projector that emits imagerendering light toward the image display screen. The image displayscreen reflects at least a portion of the image rendering light emittedfrom the light projector toward a viewer.

In an embodiment, the semi-random pattern is a two-dimensional patterngenerated from applying halftoning techniques over one or more regionsof the image display screen.

In an embodiment, the semi-random pattern is a two-dimensional patterngenerated from applying noise injection techniques over one or moreregions of the image display screen.

In an embodiment, the semi-random pattern is a two-dimensional patterngenerated from applying a combination of two or more semi-random patterngeneration techniques over one or more regions of the image displayscreen; the combination of two or more semi-random pattern generationtechniques include one or more of: halftoning techniques, noiseinjection techniques, dithering techniques, or other pattern generationtechniques.

In an embodiment, the viewer is in front of the image display screen;wherein the image display system operates in conjunction with a set ofaudio speakers behind the image display screen; the set of audiospeakers concurrently generate sounds that propagate toward the viewerthrough the perforation holes of the image display screen.

In an embodiment, the image display system operates in one of: a cinema,a theatre, an amusement park, an exhibition hall, a home setting, a bar,a club, or another venue.

In an embodiment, the viewer is located beyond a designated viewingdistance.

In an embodiment, the spatial distribution of perforation holes on theimage display screen is uniform for an area of a dimension that isvisually resolvable by the viewer located at a designated viewingdistance from the image display screen.

In an embodiment, the semi-random pattern is less prone than a regularperforation pattern to generate Moire patterns in image renderingoperations.

In an embodiment, the image display screen comprises a plurality ofseams that are joined along one or more seam edges.

In an embodiment, the spatial distribution of perforation holes on theimage display screen trends to a regular perforation pattern at the oneor more seam edges.

In an embodiment, the spatial distribution of perforation holes on theimage display screen cuts over to a regular perforation pattern at theone or more seam edges.

In various example embodiments, an apparatus, a system, an apparatus, orone or more other computing devices performs any or a part of theforegoing methods as described. In an embodiment, a non-transitorycomputer readable storage medium stores software instructions, whichwhen executed by one or more processors cause performance of a method asdescribed herein.

Note that, although separate embodiments are discussed herein, anycombination of embodiments and/or partial embodiments discussed hereinmay be combined to form further embodiments.

6. Implementation Mechanisms—Hardware Overview

According to one embodiment, the techniques described herein areimplemented by one or more special-purpose computing devices. Thespecial-purpose computing devices may be hard-wired to perform thetechniques, or may include digital electronic devices such as one ormore application-specific integrated circuits (ASICs) or fieldprogrammable gate arrays (FPGAs) that are persistently programmed toperform the techniques, or may include one or more general purposehardware processors programmed to perform the techniques pursuant toprogram instructions in firmware, memory, other storage, or acombination. Such special-purpose computing devices may also combinecustom hard-wired logic, ASICs, or FPGAs with custom programming toaccomplish the techniques. The special-purpose computing devices may bedesktop computer systems, portable computer systems, handheld devices,networking devices or any other device that incorporates hard-wiredand/or program logic to implement the techniques.

For example, FIG. 5 is a block diagram that illustrates a computersystem 500 upon which an example embodiment of the invention may beimplemented. Computer system 500 includes a bus 502 or othercommunication mechanism for communicating information, and a hardwareprocessor 504 coupled with bus 502 for processing information. Hardwareprocessor 504 may be, for example, a general purpose microprocessor.

Computer system 500 also includes a main memory 506, such as a randomaccess memory (RAM) or other dynamic storage device, coupled to bus 502for storing information and instructions to be executed by processor504. Main memory 506 also may be used for storing temporary variables orother intermediate information during execution of instructions to beexecuted by processor 504. Such instructions, when stored innon-transitory storage media accessible to processor 504, rendercomputer system 500 into a special-purpose machine that is customized toperform the operations specified in the instructions.

Computer system 500 further includes a read only memory (ROM) 508 orother static storage device coupled to bus 502 for storing staticinformation and instructions for processor 504.

A storage device 510, such as a magnetic disk or optical disk, solidstate RAM, is provided and coupled to bus 502 for storing informationand instructions.

Computer system 500 may be coupled via bus 502 to a display 512, such asa liquid crystal display, for displaying information to a computer user.An input device 514, including alphanumeric and other keys, is coupledto bus 502 for communicating information and command selections toprocessor 504. Another type of user input device is cursor control 516,such as a mouse, a trackball, or cursor direction keys for communicatingdirection information and command selections to processor 504 and forcontrol ling cursor movement on display 512. This input device typicallyhas two degrees of freedom in two axes, a first axis (e.g., x) and asecond axis (e.g., y), that allows the device to specify positions in aplane.

Computer system 500 may implement the techniques described herein usingcustomized hard-wired logic, one or more ASICs or FPGAs, firmware and/orprogram logic which in combination with the computer system causes orprograms computer system 500 to be a special-purpose machine. Accordingto one embodiment, the techniques herein are performed by computersystem 500 in response to processor 504 executing one or more sequencesof one or more instructions contained in main memory 506. Suchinstructions may be read into main memory 506 from another storagemedium, such as storage device 510. Execution of the sequences ofinstructions contained in main memory 506 causes processor 504 toperform the process steps described herein. In alternative embodiments,hard-wired circuitry may be used in place of or in combination withsoftware instructions.

The term “storage media” as used herein refers to any non-transitorymedia that store data and/or instructions that cause a machine tooperation in a specific fashion. Such storage media may comprisenon-volatile media and/or volatile media. Non-volatile media includes,for example, optical or magnetic disks, such as storage device 510.Volatile media includes dynamic memory, such as main memory 506. Commonforms of storage media include, for example, a floppy disk, a flexibledisk, hard disk, solid state drive, magnetic tape, or any other magneticdata storage medium, a CD-ROM, any other optical data storage medium,any physical medium with patterns of holes, a RAM, a PROM, and EPROM, aFLASH-EPROM, NVRAM, any other memory chip or cartridge.

Storage media is distinct from but may be used in conjunction withtransmission media. Transmission media participates in transferringinformation between storage media. For example, transmission mediaincludes coaxial cables, copper wire and fiber optics, including thewires that comprise bus 502. Transmission media can also take the formof acoustic or light waves, such as those generated during radio-waveand infra-red data communications.

Various forms of media may be involved in carrying one or more sequencesof one or more instructions to processor 504 for execution. For example,the instructions may initially be carried on a magnetic disk or solidstate drive of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over atelephone line using a modem. A modem local to computer system 500 canreceive the data on the telephone line and use an infra-red transmitterto convert the data to an infra-red signal. An infra-red detector canreceive the data carried in the infra-red signal and appropriatecircuitry can place the data on bus 502. Bus 502 carries the data tomain memory 506, from which processor 504 retrieves and executes theinstructions. The instructions received by main memory 506 mayoptionally be stored on storage device 510 either before or afterexecution by processor 504.

Computer system 500 also includes a communication interface 518 coupledto bus 502. Communication interface 518 provides a two-way datacommunication coupling to a network link 520 that is connected to alocal network 522. For example, communication interface 518 may be anintegrated services digital network (ISDN) card, cable modem, satellitemodem, or a modem to provide a data communication connection to acorresponding type of telephone line. As another example, communicationinterface 518 may be a local area network (LAN) card to provide a datacommunication connection to a compatible LAN. Wireless links may also beimplemented. In any such implementation, communication interface 518sends and receives electrical, electromagnetic or optical signals thatcarry digital data streams representing various types of information.

Network link 520 typically provides data communication through one ormore networks to other data devices. For example, network link 520 mayprovide a connection through local network 522 to a host computer 524 orto data equipment operated by an Internet Service Provider (ISP) 526.ISP 526 in turn provides data communication services through the worldwide packet data communication network now commonly referred to as the“Internet” 528. Local network 522 and Internet 528 both use electrical,electromagnetic or optical signals that carry digital data streams. Thesignals through the various networks and the signals on network link 520and through communication interface 518, which carry the digital data toand from computer system 500, are example forms of transmission media.

Computer system 500 can send messages and receive data, includingprogram code, through the network(s), network link 520 and communicationinterface 518. In the Internet example, a server 530 might transmit arequested code for an application program through Internet 528, ISP 526,local network 522 and communication interface 518.

The received code may be executed by processor 504 as it is received,and/or stored in storage device 510, or other non-volatile storage forlater execution.

7. Equivalents, Extensions, Alternatives and Miscellaneous

In the foregoing specification, example embodiments of the inventionhave been described with reference to numerous specific details that mayvary from implementation to implementation. Thus, the sole and exclusiveindicator of what is the invention, and is intended by the applicants tobe the invention, is the set of claims that issue from this application,in the specific form in which such claims issue, including anysubsequent correction. Any definitions expressly set forth herein forterms contained in such claims shall govern the meaning of such terms asused in the claims. Hence, no limitation, element, property, feature,advantage or attribute that is not expressly recited in a claim shouldlimit the scope of such claim in any way. The specification and drawingsare, accordingly, to be regarded in an illustrative rather than arestrictive sense.

Aspects of some embodiments include the following enumerated exampleembodiments (EEEs):

-   EEE1. An image display system comprising:    -   an image display screen that comprises a spatial distribution of        perforation holes forming a semi-random pattern to reduce Moire        patterns in image rendering operations;    -   wherein the semi-random pattern represents a spatially random        perforation pattern free of relatively low frequency patterns        prone to generate the Moire patterns in the image rendering        operations;    -   a light projector configured to emit image rendering light        toward the image display screen;    -   wherein the image display screen is configured to reflect at        least a portion of the image rendering light emitted from the        light projector toward a viewer.-   EEE2. The image display system of EEE1, wherein the semi-random    pattern is a two-dimensional pattern generated from applying    halftoning techniques over one or more regions of the image display    screen.-   EEE3. The image display system of EEE1, wherein the semi-random    pattern is a two-dimensional pattern generated from applying noise    injection techniques over one or more regions of the image display    screen.-   EEE4. The image display system of EEE1, wherein the semi-random    pattern is a two-dimensional pattern generated from applying a    combination of two or more semi-random pattern generation techniques    over one or more regions of the image display screen; wherein the    combination of two or more semi-random pattern generation techniques    include one or more of: halftoning techniques, noise injection    techniques, dithering techniques, or other pattern generation    techniques.-   EEE5. The image display system of any one of EEEs 1 to 4, wherein    the viewer is in front of the image display screen; wherein the    image display system is configured to operate in conjunction with a    set of audio speakers behind the image display screen; wherein the    set of audio speakers is configured to concurrently generate sounds    that propagate toward the viewer through the perforation holes of    the image display screen.-   EEE6. The image display system of any one of EEEs 1 to 5, wherein    the image display system operates in one of: a cinema, a theatre, an    amusement park, an exhibition hall, a home setting, a bar, a club,    or another venue.-   EEE7. The image display system of any one of EEEs 1 to 6, wherein    the viewer is located beyond a designated viewing distance.-   EEE8. The image display system of any one of EEEs 1 to 7, wherein    the spatial distribution of perforation holes on the image display    screen is uniform for an area of a dimension that is visually    resolvable by the viewer located at a designated viewing distance    from the image display screen.-   EEE9. The image display system of any one of EEEs 1 to 8, wherein    the semi-random pattern is less prone than a regular perforation    pattern to generate Moire patterns in image rendering operations.-   EEE10. The image display system of any one of EEEs 1 to 9, wherein    the image display screen comprises a plurality of webs that are    joined along one or more seam edges.-   EEE11. The image display system of EEE10, wherein the spatial    distribution of perforation holes on the image display screen trends    to a regular perforation pattern at the one or more seam edges.-   EEE12. The image display system of EEE 10, wherein the spatial    distribution of perforation holes on the image display screen cuts    over to a regular perforation pattern at the one or more seam edges.-   EEE13. A method, the method comprising:    -   applying one or more perforation hole pattern methods to        generate a spatial distribution of perforation holes forming a        semi-random pattern for an image display screen to reduce Moire        patterns in image rendering operations;    -   wherein the semi-random pattern represents a spatially random        perforation pattern free of relatively low frequency patterns        prone to generate the Moire patterns in the image rendering        operations;    -   perforating the image display screen with the spatial        distribution of perforation holes forming the semi-random        pattern;    -   emitting, by a light projector, image rendering light toward the        image display screen that is installed in an image rendering        environment;    -   reflecting, by the image display screen, at least a portion of        the image rendering light emitted from the light projector        toward a viewer.-   EEE14. A non-transitory computer readable storage medium, storing    software instructions, which when executed by one or more processors    cause the method recited in EEE 13 to be performed.-   EEE15. An apparatus comprising one or more processors and one or    more storage media, storing a set of instructions, which when    executed by one or more processors cause the method recited in EEE    13 to be performed.

The invention claimed is:
 1. An image display screen comprising: aspatial distribution of perforation holes forming a semi-random patternto reduce Moire patterns in image rendering operations; wherein theimage display screen is configured to reflect at least a portion ofimage rendering light emitted from a light projector toward a viewer;wherein the image display screen comprises a plurality of webs that arejoined along one or more seam edges; and wherein the spatialdistribution of perforation holes on the image display screen trendsfrom the semi-random pattern to a regular perforation pattern toward theone or more seam edges.
 2. The image display screen of claim 1, whereinthe semi-random pattern is a two-dimensional pattern generated fromapplying halftoning techniques over one or more regions of the imagedisplay screen.
 3. The image display screen of claim 1, wherein thesemi-random pattern is a two-dimensional pattern generated from applyingnoise injection techniques over one or more regions of the image displayscreen.
 4. The image display screen of claim 1, wherein the semi-randompattern is a two-dimensional pattern generated from applying acombination of two or more semi-random pattern generation techniquesover one or more regions of the image display screen; wherein thecombination of two or more semi-random pattern generation techniquesinclude one or more of: halftoning techniques, noise injectiontechniques, dithering techniques, or other pattern generationtechniques.
 5. The image display screen of claim 1, wherein the vieweris in front of the image display screen; wherein the image displayscreen is configured to operate in conjunction with a set of audiospeakers behind the image display screen; wherein the perforation holesof the image display screen are configured to allow sounds generated bythe set of audio speakers to pass through the image display screentoward the viewer.
 6. The image display screen of claim 1, configured tooperate in one of: a cinema, a theatre, an amusement park, an exhibitionhall, a home setting, a bar, a club, or another venue.
 7. The imagedisplay screen of claim 1, wherein the viewer is located beyond adesignated viewing distance from the image display screen.
 8. The imagedisplay screen of claim 1, wherein the spatial distribution ofperforation holes on the image display screen is uniform for an area ofa dimension that is visually resolvable by the viewer located at adesignated viewing distance from the image display screen.
 9. The imagedisplay screen of claim 1, wherein the semi-random pattern is less pronethan a regular perforation pattern to generate Moire patterns in imagerendering operations.
 10. A method of manufacturing an image displayscreen, comprising: applying one or more perforation hole patternmethods to generate a spatial distribution of perforation holes forminga semi-random pattern for the image display screen to reduce Moirepatterns in image rendering operations; perforating the image displayscreen with the spatial distribution of perforation holes forming thesemi-random pattern; providing a plurality of webs that are joined alongone or more seam edges of the image display screen; wherein the spatialdistribution of perforation holes on the image display screen trendsfrom the semi-random pattern to a regular perforation pattern toward theone or more seam edges.
 11. The method of claim 10, wherein thesemi-random pattern is a two-dimensional pattern generated from applyinghalftoning techniques over one or more regions of the image displayscreen.
 12. The method of claim 10, wherein the semi-random pattern is atwo-dimensional pattern generated from applying noise injectiontechniques over one or more regions of the image display screen.
 13. Themethod of claim 10, wherein the semi-random pattern is a two-dimensionalpattern generated from applying a combination of two or more semi-randompattern generation techniques over one or more regions of the imagedisplay screen; wherein the combination of two or more semi-randompattern generation techniques include one or more of: halftoningtechniques, noise injection techniques, dithering techniques, or otherpattern generation techniques.
 14. The method of claim 10, wherein aviewer is in front of the image display screen; wherein the imagedisplay screen is configured to operate in conjunction with a set ofaudio speakers behind the image display screen; and wherein theperforation holes of the image display screen are configured to allowsounds generated by the set of audio speakers to pass through the imagedisplay screen toward the viewer.
 15. The method of claim 10, whereinthe image display screen operates in one of: a cinema, a theatre, anamusement park, an exhibition hall, a home setting, a bar, a club, oranother venue.
 16. The method of claim 10, wherein a viewer is locatedbeyond a designated viewing distance from the image display screen. 17.The method of claim 10, wherein the spatial distribution of perforationholes on the image display screen is uniform for an area of a dimensionthat is visually resolvable by a viewer located at a designated viewingdistance from the image display screen.
 18. The method of claim 10,wherein the semi-random pattern is less prone than a regular perforationpattern to generate Moire patterns in image rendering operations.